Conditioning of crude oil charge to centrifuge for asphalt improvement



June 7, 1966 s. A. MOYER 3,255,104

CONDITIONING OF CRUDE OIL CHARGE TO- CENTRIFUGE FOR ASPHALT IMPROVEMENT Filed July 5, 1962 RAW CRUDE CENTRIFUGED 9 CRUDE em la 20 3o INVENTOR.

c. A. MOY ER A T TORNEYS United States Patent 3,255,104 CONDITIONING 0F CRUDE OIL CHARGE T0 CEN- TRIFUGE FOR ASPHALT IMPROVEMENT Golden A. Moyer, Bartlesville, Okla, assignor to Phillips Petroleum Company, a corporation of Delaware Filed July 5, 1962, Ser. No. 207,617 Claims. (Cl. 208-177) This invention relates to treatment of an asphalt-containing crude oil to make the crude oil suitable for production of quality asphalt. In one aspect, it relates to a method and apparatus for treating an asphaltcontaining crude oil which normally yields asphaltic products having positive Oliensis spot tests so that the crude oil will yield asphaltic products having negative Oliensis spot tests. In another aspect, it relates to a means and a method fortreating by centrifugal separation an asphalt-containing crude oil, which normally yields asphalt products having positive Oliensis spot tests, for production of a crude oil suitable for yielding asphaltic materials having negative Oliensis spot tests. In another aspect, it relates to a centrifuging process for the removal of impurities of crude oil. In yet another aspect, it relates to the separation of solids, semi-solids, and heavy liquid materials, all as impurities from an asphaltcontaining crude oil, by centrifugal action, the crude oil normally causing positive Oliensis spot tests in subsequently produced asphaltic products, for the production of asphaltic products having negative Oliensis spot tests.

This invention is also concerned with a method for improving or increasing the amount of crude oil that can be centrifuged per unit of time, the crude oil being a relatively viscous crude oil.

Crude oils which are treated by centrifuging according to this invention are such oils as Rangely, Colorado; Williston Basin, North Dakota; Bowes Dome, Montana; and Santa Maria, California, crude oils. 7 Crude oils from these areas are merely examples of crude oils suitable for treatment according to this invention.

These crude oils contain one or more of solid, semisolid, and heavy liquid materials within a range of about 0.5 to about 10 percent on a weight basis. These materials are believed clearly to cause asphaltic products made from crude oils containing them to exhibitpositive Oliensis spot tests. These crude oils when centrifuged for the removal of these materials yield asphaltic materials having negative Oliensis spot tests. Because these crude oils are relatively viscous, centrifuging of the oils as received is relatively slow. Thus, to so process such a volume of the crude oil of this type as a refinery charge stock requires a plurality of centrifuges operated in parallel. It is realized that such equipment is relatively expensive not only as items of capital investment but electrical power and steam costs for their operation are also quite high. It has been found by heating the crude oil in a crude oil storage tank in order to make the oil sufficiently fluid for ease of centrifuging that at least a portion of the above-mentioned solid, semi-solid, and heavy liquid materials become dissolved. The dissolving is to such an extent that the asphaltic products produced from the heated oil exhibit positive Oliensis spot tests or in some instances the spot tests are on the-borderline between positive and negative. Even this latter type of spot test is unsuitable for specification purposes. It is realized that heating a large volume of oil in a tank results in many instances in overheating of the oil in the immediate vicinity of the heating coil.

An object of this invention is to provide a method and apparatus for removal of solid, semi-solid, and heavy liquid materials contained in many crude oils which materials cause positive Oliensis spot tests on subsequently "ice produced asphaltic products. Another object of this invention is to provide meansand method for increasing for increasing the rate of centrifuging of such crude oils oil.

for removal of the above-mentioned undesirable impurities. Still other objects and advantages of this invention will be realized upon reading the following description which, taken with the'attached drawing, forms a part of this specification.

In the drawing, FIGURE 1 illustrates, in diagrammatic form, an arrangement of apparatus parts for carrying out the method of this invention. FIGURE 2 illustrates alternate means for carrying out the process of this invention.

In one embodiment of this invention, I provide a low MTD (low mean temperature differencelheat exchange for the crude oil between the crude oil storage tank and the centrifuges. In this embodiment, I heat to a relatively low temperature a portion of the processed and impurity-free crude oil and then mix this slightly heated impurity-free crude oil with the original crude oil prior to centrifuging in such a manner as to provide turbulent and thorough mixing of the oil with the heated recycle In this manner, a small volume of recycle oil, free from impurities, is heated and obviously impurities cannot redisso-lve in this oil because they are not present. Then, upon mixing this slightly heated oil with the original raw crude oil in a turbulent mixing manner, direct heat exchange is rapid and without substantial dissolving of the impurities desired to be separated out by centrifugal action. In another embodiment, this invention involves heat exchanging the entire volume of raw crude oil with water heated to a temperature such as will not dissolve the impurity in the crude oil upon heat exchange therewith.

It has been found-that uponheating thecrude oil to a temperature of 200 to 300 F. to reduce its viscosity to such an extent that centrifuging is rapid, the impurities desired to be removed from the crude oil dissolve in the crude oil and are not subject to removal in the centrifuge. Upon heating the oil to a relatively high temperature, the purification step by centrifuging is ineifective. This heated oil when cooled by heat exchange precipitates the above-mentioned impurities so slowly that centrifuging is ineffective. Thus, according to this invention, the crude oil is very gently heated, that is, to such a relatively low temperature that the desired impurities are not redissolved and can be removed from the crude oil. Yet the crude oil is heated to a slightly higher degree than its average storage temperature so that centrifuging is considerably more rapid than the oil not so heated.

In FIGURE 1, reference numeral 1 identifies a conduit passing the raw crude oil from a crude oil storage tank, not shown, to a pump 2 which charges the crude oil through a conduit 3, a reduced diameter mixing conduit 5a, and subsequent centrifugal apparatus. Conduit 3 connects the outlet of pump 2 with the large diameter end of a pipe reducer 4, the small diameter end of which is connected to the first conduit 5.

The outlet end of mixing conduit 5a is connected with the small diameter end of another reducer 4 which is connected to the large diameter conduit 6 for passage of the material to a plurality of centrifuges 8. Several branched conduits 6a are provided with valves 7 and are connected to the several centrifuges as shown. Outlet conduits 9 lead processed crude oil from the several centrifuges to an outlet or disposal conduit 11. The several outlet conduits 9 are also provided with manually operable valves 7 as shown. Conduits 10 Ieadthe underflow, that is the impurities processed from the crude oil, from the several centrifuges and the combined material passes through a conduit 12 for such disposal as desired.

A recycle conduit 13 is connected at one end with the conduit 11 and is provided with a pump 14, a heat exchanger 15, a motor valve 24, and terminates as a manifold conduit 20. From this manifold conduit 20, several branched conduits 21 lead to a plurality of pipe Ts each connected with a separate section of the mixing conduit 5a. A thermocouple 17 is inserted into conduit 13 just downstream from heat exchanger 15 as regards direction of flow of oil. A temperature controller 18 regulates the rate of steam flow in conduit 16 by manipulation of motor valve 19. The motor valve 24 just downstream of thermocouple 17 is manipulated by the temperature controller 23 in response to a temperature as 'sensed by thermocouple 22 in conduit 6.

In actual operation, the thermocouple 22 senses the temperature of the mixed and warm oil and manipulates motor valve 24 by way of controller 23 to maintain the crude oil in conduit 6 at a desired predetermined temperature. This temperature obviously is intended to be sufiiciently high to promote increased centrifuging in the several centrifuges and yet not so high as to dissolve the impurity in the crude oil. The temperature controller 18 manipulates motor valve 19 to regulate the rate of flow of steam from conduit 16 to heat exchanger 15, in response to the temperature of a heated recycle oil to provide properly heated oil for passing through manifold 20 and branched conduit 21 to the several mixing Ts.

Specific example In one instance, the temperature of the crude oil flowing through conduit 3 was 40 F. and the volume of oil flowing was approximately 8,770 barrels per day. Conduit 3 was a six-inch diameter pipe. The mixing conduit 5a comprised a plurality of four pipe Ts of 3-inch diameter with l-inch diameter side inlets. The temperature of the crude oil issuing from the downstream end of the mixing conduit 5a was 65 F. and its volume was approximately 10,550 barrels per day. This oil was filtered in centrifuges 8 and approximately 1,780 barrels per day were removed from the centrifuged oil and passed through conduit 13 under the influence of pump 14. The oil rate in conduit 13 was 52 gallons per minute and conduit 13 was a 2-inch pipe. This oil was heated with steam in exchanger 15 to a temperature of about 177 F. Oil heated to this temperature was approximately equally divided in manifold 20 and the respective portions passed at high velocity through one-inch pipe conduit 21 to the one-inch inlets of the several pipe T5 5. With 8,770 barrels per dayof oil flowing through a 3- inch diameter mixing section 5a, flow therein was very turbulent. This turbulent flow thoroughly and rapidly mixed the 177 F. oil with the 40 F. raw oil. Thus with this rapid mixing with the heated oil of a relatively medium temperature impurities in the raw crude oil were not redissolved.

In the embodiment illustrated in FIGURE 2, conduits 1a, 3a, 6b, 60, 9a, a, 11a, and 12a correspond to pipes 1, 3, 6, 6a, 9, 10, 11 and 12, respectively, of FIGURE 1. Pump 2a corresponds to the pump 2 of the FIGURE 1. Conduit 3a discharges the raw crude oil from the storage tank, not shown, to a heat exchanger 31 in which warm water at about 112 F. is circulated. This water indirectly heat exchanges with and warms the crude oil from about 40 F. to about 65 F. with the water outlet temperature being about 92 F. A body of water 42 is provided in tank 41 which is provided with a conduit 43 with openings for distribution of steam for heating the water. 'Flow of steam in conduit 43 is regulated by a motor valve 38 as manipulated by temperature controller 40 in response to the temperature as sensed by a thermocouple 39. This heated Water is passed through conduit 33 by a pump 34 and the rate of flow is regulated by temperature controller 36 manipulating motor valve 37 in response to temperature as sensed by a temperature sensing device such as a thermocouple 35 in conduit 6b. A by-pass conduit 32 is connected with conduit 3a and conduit 6b around heat exchanger 31 in case it is ever necessary to repair, clean or otherwise maintain the heat exchanger.

In the instant FIGURE 2, for heating 8,770 barrels of crude oil per day from 40 to F., 117 gallons of water per minute at 112 F. are passed through conduit 33 which is a three-inch diameter conduit. Conduits 3a and 6b are six-inch conduits. Tank 41 is a 10-barrel tank in which the water is heated to the above-mentioned 112 F. by steam at the rate of 1070 pounds per hour from conduit 43.

For treating the above-mentioned Y volumes of raw crude oil as regards heating, heat exchanger 15 and heat exchanger 31 have a duty of 1,170,000 B.t.u.s per hour. In the embodiment of FIGURE 1, the centrifuge and impurity-free crude oil issues from the centrifuges at a temperature of about 65 F. and the portion of this oil cycled through conduit 13 is heated from 65 F. to'

about 177 F. in exchanger 15. The above-mentioned 1,170 barrels per day of processed or centrifuged crude oil pass through conduit 13 for heating purposes represent approximately 20% of the 8,770 barrels per day of raw crude oil filtered in this operation.

The three-inch diameter mixing conduit 5a in one instance is approximately 30 feet in length with the several mixing Ts 5 being separated by small length of 3- inch pipe. The Ts 5 can be sections of pipe provided with flanges and 1-inch diameter side inlets.

Other-suitable mixing means than that illustrated and described can, if desired, be employed.

While certain embodiments of the invention have been described for illustrative purposes, the invention obviously is not limited thereto.

The process of this invention is equally applicable to filtration of such crude oils by conventional filters as to the centrifugal separation herein described.

I claim:

1. In a process for removing particulate solid to semisolid material from a relatively cold crude oil containing same wherein a first stream of said crude oil is passed thru a centrifuging zone to separate same into a second stream of oil of substantially lower concentration of said material than said first stream and a third stream of oil of substantially higher concentration of said material than said first stream, the improvement comprises the steps of:

( 1) passing a fourth stream of centrifuged crude oil substantially free of solid to semi-solid material and lighter than said first stream into said first stream upstream of the centrifuging zone at a substantially higher temperature than the temperature of said first stream but below a temperature which causes said material to go into solution in the stream resulting from step 2;

(2) rapidly mixing said first and fourth streams to raise the temperature of the oil of said first stream to lower the viscosity thereof without dissolving said particulate material; and

(3) passing the resulting less viscous stream of oil from step 2 thru the centrifuging zone to separate same into said second and third streams.

2. The improvement in claim 1 wherein said fourth stream is obtained by recycling a substantial portion of said second stream thru a heat exchange zone before passing same into said first stream.

3. The improvement of claim 2 wherein the volume and temperature of the fourth stream are controlled so as to heat said first stream to a temperature of at least 40 F. and not substantially above F.

4. The improvement of claim 1 wherein said fourth stream is injected at several spaced points along the line of flow of said first stream.

5. A process for removing particulate solid to semisolid material from a crude oil containing same, said crude oil being at a temperature of not more than about 40 R, which comprises the steps of:

(1) intimately mixing with said stream of crude oil 'a second stream of oil at a substantially higher temperature than 40 B, said second stream of oil being a portion of the third stream of step 2 and substantially free of solid to semi-solid material and lighter than said crude oil, to raise the temperature of said stream of crude oil to a selected temperature in the range of 40 to 70 F. and substantially above its original temperature;

(2) passing the resulting heated mixed stream of step 1 thru a centrifuging zone so as to separate said mixed stream into a third stream of lighter oil having a relatively low concentration of said material and a fourth stream of heavier oil having a relatively high concentration of said material; and

(3) recovering said third stream as a product of the process.

6. The process of claim 5 including the step of:

(4) recycling a portion of the third stream of step 2 thru a heater into the stream of crude oil of step 1 as said second stream at several points along the line of flow of said stream of crude oil. 3

7. Apparatus for removing solid to semi-solid material from crude oil, comprising in combination:

- (a) mixing means for mixing separate first and second liquid streams having separate inlets for said streams;

(b) a centrifugal separator downstream of the mixing means of (a) connected by conduit therewith;

(c) an efliuent line leading from the separator of (b) for a lighter stream of liquid;

((1) an efiluent line leading from the separator of (b) for a heavier stream of liquid;

(e) a recycle line connecting the eflluent line of (c) with one of the inlets of the mixing mean of (a); and

(f) heating means in said recycle line.

8. The apparatus of claim 7 including:

(g) a motor valve in the recycle line of (e);

(h) temperature sensing and transmitting means sensitive to the temperature in the conduit of (b); and

(i) a temperature controller responsive tov the temperature transmitting means of (h) in actuating control of the motor valve of (g). 9. The apparatus of claim 8 wherein the heating means 5 of (f) is an indirect heat exchanger having a hot fluid line leading thereinto and including:

(j) a motor valve in said hot fluid line;

(k) temperature sensing and transmitting means responsive to temperature in the recycle line of (e) downstream of said heat exchanger; and

(l) a temperature controller responsive to the temperature transmitting means of (k) in actuating control of the motor valve of (j).

10. Apparatus for removing solid to semi-solid material from crude oil comprising in combination:

(a) a centrifugal separator having a feed inlet line and a pair of eflluent lines for a heavier and lighter stream;

(b) means in the ,feed inlet line of (a) for mixing a heating fluid with the feed therein;

(0) a line connected with the eflluent line for lighter fluid of (a) and with the means of (b) for supplying heating fluid thereto;

((1) means in the line of (c) for controlling the temperature of thefluid therein; and

(e) means in the line of (c) for controlling the flow rate of fluid therethru in response to the temperature of the eflluent liquid in the feed inlet line of (a) intermediate the heating means of (b) and the separator of (a).

References Cited by the Examiner UNITED STATES PATENTS DELBERT E. GANTZ, Primary Examiner.

DANIEL E. WYMAN, Examiner.

H. LEVINE, Assistant Examiner. 

1. IN A PROCESS FOR REMOVING PARTICULATE SOLID TO SEMISOLID MATERIAL FROM A RELATIVELY COLD CRUDE OIL CONTAINING SAME WHEREIN A FIRST STREAM OF SAID CRUDE OIL IS PASSED THRU A CENTRIFUGING ZONE TO SEPARATE SAME INTO A SECOND STREAM OF OIL OF SUBSTANTIALLY LOWER CONCENTRATION OF SAID MATERIAL THAN SAID FIRST STREAM AND A THIRD STREAM OF OIL OF SUBSTANTIALLY HIGHER CONCENTRATION OF SAID MATERIAL THAN SAID FIRST STREAM, THE IMPROVEMENT COMPRISES THE STEPS OF: (1) PASSING A FOURTH STREAM OF CENTRIFUGED CRUDE OIL SUBSTANTIALLY FREE OF SOLID TO SEMI-SOLID MATERIAL AND LIGHTER THAN SAID FIRST STREAM INTO SAID FIRST STREAM UPSTREAM OF THE CENTRIFUGING ZONE AT A SUBSTANTIALLY HIGHER TEMPERATURE THAN THE TEMPERATURE OF SAID FIRST STREAM BUT BELOW A TEMPERATURE WHICH CAUSES SAID MATERIAL TO GO INTO SOLUTION IN THE STREAM RESULTING FROM STEP 2; (2) RAPIDLY MIXING SAID FIRST AND FOURTH STREAMS TO RAISE THE TEMPERATURE OF THE OIL OF SAID FIRST STREAM TO LOWER THE VISCOSITY THEREOF WITHOUT DISSOLVING SAID PARTICULATE MATERIAL; AND (3) PASSING THE RESULTING LESS VISCOUS STREAM OF OIL FROM STEP 2 THRU THE CENTRIFUGING ZONE TO SEPARATE SAME INTO SAID SECOND AND THIRD STREAMS. 